State of Minnesota, Respondent, vs. Tacuma Jawanza Mwanza, Appellant.

may not be cited except as provided by

Minn. Stat. § 480 A. 08, subd. 3 (1996).

 STATE OF MINNESOTA

 IN COURT OF APPEALS

 C3-97-1376

State of Minnesota,

Respondent,

vs.

Tacuma Jawanza Mwanza,

Appellant.

 Filed June 9, 1998

 Affirmed in part, reversed in part, and remanded

 Willis, Judge

Hennepin County District Court

File No. 96208941

Hubert H. Humphrey III, Attorney General, 1400 NCL Tower, 445 Minnesota Street, St. Paul, MN 55101; and Michael O. Freeman, Hennepin County Attorney, Donna J. Wolfson, Assistant County Attorney, C-2000 Government Center, Minneapolis, MN 55487 (for respondent)

Lawrence W. Pry, Assistant State Public Defender, 875 Summit Avenue, Room 371, St. Paul, MN 55105 (for appellant)

Considered and decided by Willis, Presiding Judge, Randall, Judge, and Klaphake, Judge.

 U N P U B L I S H E D O P I N I O N

 WILLIS, Judge

Tacuma Jawanza Mwanza appeals from his convictions of second-degree assault in violation of Minn. Stat. § 609.222, subd. 1, and fourth-degree assault in violation of Minn. Stat. § 609.2231, subd. 1. We affirm the fourth-degree assault conviction, reverse the second-degree assault conviction, and remand for resentencing.

 FACTS

On November 27, 1996, Officer Roderic Weber was dispatched to a residential treatment facility to arrest appellant Tacuma Mwanza, a.k.a. Anthony Sweats, on an outstanding warrant. When Officer Weber reached for Mwanza's right hand to handcuff him, Mwanza pushed Weber back with his left hand and swung his right fist at Weber's face. Officer Weber briefly lost his balance, and Mwanza ran toward a flight of stairs.

Officer Weber testified that he caught up to Mwanza on the staircase, where Mwanza grabbed a wooden baluster supporting the stair railing and swung it with both hands at Weber's head.[1] Officer Weber ducked and blocked the blow with his left arm, and the baluster broke in two. Mwanza continued up the stairs, and near the top step, he raised his right leg and kicked at Officer Weber, striking him in the leg and knocking him back several steps. Officer Weber recovered his balance, but Mwanza escaped through the front door.

Gregory Fletcher, a case manager at the treatment facility, testified that he witnessed the incident with the baluster and that Officer Weber did not appear to have been injured. Officer Weber testified that his left arm and right leg were bruised where he was struck, first by the baluster and then by Mwanza's kick. Officer Weber did not need medical attention for the bruises.

Following a jury trial, Mwanza was convicted of both second- and fourth-degree assault. The district court sentenced Mwanza to an executed prison term of 63 months and ordered that he serve that sentence consecutively to a prior, unexpired sentence. On its own motion, the court later corrected Mwanza's sentence to 36 months. This appeal followed.

 D E C I S I O N

This court must review the record and legitimate inferences from the record in the light most favorable to the conviction to determine whether the fact-finder could reasonably have concluded the defendant was guilty of the charged offense beyond a reasonable doubt. Dale v. State, 535 N.W.2d 619, 623 (Minn. 1995).

To convict Mwanza for second-degree assault, the state had to prove that (1) Mwanza assaulted Officer Weber and (2) he used a dangerous weapon in the assault. See Minn. Stat. § 609.222, subd. 1 (1996) (defining assault in the second degree with a dangerous weapon). Mwanza challenges only the second element, arguing that the state failed to prove that the baluster was a dangerous weapon or that the manner in which it was used made it a dangerous weapon.

A dangerous weapon includes "any * * * device or instrumentality that, in the manner it is used or intended to be used, is calculated or likely to produce death or great bodily harm." Minn. Stat. § 609.02, subd. 6 (1996).

"Great bodily harm" means bodily injury which creates a high probability of death, or which causes serious permanent disfigurement, or which causes a permanent or protracted loss or impairment of the function of any bodily member or organ or other serious bodily harm.

Minn. Stat. § 609.02, subd. 8 (1996).

In State v. Basting, 572 N.W.2d 281, 285 (Minn. 1997), the court stated that:

When determining whether an object, even an inherently dangerous object, is a dangerous weapon, the court must examine not only the nature of the object itself, but also the manner in which it was used.

The Basting court held that the manner in which the defendant, a professionally trained boxer, used his fist did not constitute the use of dangerous weapon. 572 N.W.2d at 285. In other cases involving defendants' use of objects that are not inherently dangerous, courts have considered factors such as the duration of the assault in determining if the manner in which an object was used made it capable of causing great bodily harm. See State v. Elkins, 346 N.W.2d 116, 118-19 (Minn. 1984) (discussing, in context of sentencing appeal, prolonged beating of six-year-old victim with a wooden chair rung, causing child to be hospitalized for severe bruising); State v. Trott, 338 N.W.2d 248, 252 (Minn. 1983) (discussing defendant's beating of victim for up to ten minutes with 3' long, 2" wide, 3/4" thick wooden board, court stated that "[s]ome things that are not ordinarily thought of as dangerous weapons become dangerous weapons if so used").

We conclude that the evidence here is insufficient to support a finding that Mwanza used the baluster in a manner calculated to inflict great bodily harm. Mwanza swung the baluster once while attempting to escape, and it broke on impact with the officer's arm. As a matter of law, in the manner in which it was used, the baluster was not a dangerous weapon. We reverse Mwanza's conviction of second-degree assault.

Because we have reversed Mwanza's second-degree assault conviction, we do not address his ineffective assistance of counsel claim based on his attorney's alleged failure to secure witness testimony concerning the baluster incident. We also address only those arguments in Mwanza's pro se brief that relate to his fourth-degree assault conviction.

In a supplemental pro se brief, Mwanza claims he received notice on the day of trial of an amendment to the complaint adding the fourth-degree assault charge and that he was denied effective assistance of counsel when his attorney failed to request a continuance to investigate the new charge. But the record shows that Mwanza's attorney received earlier notice of the amendment; she mentioned the fourth-degree assault charge at a pretrial conference six days before trial. Further, little, if any, additional investigation was required because information regarding the elements of the new charge was already provided in reports describing the charge of second-degree assault. And before trial, the district court may "freely permit amendments to the complaint so as to charge additional offenses." State v. Pettee, 538 N.W.2d 126, 132 (Minn. 1995) (discussing Minn. R. Crim. P. 3.04, subd. 2), cert. denied, 517 U.S. 1146, 116 S. Ct. 1444 (1996). The district court did not err in permitting the state to amend the complaint before trial.

Mwanza also argues that the district court abused its discretion in allowing Officer Weber to testify regarding his injuries rather than requiring expert medical testimony. Mwanza failed to object to the admission of this testimony at trial and, therefore, has waived his right to raise the issue on appeal. See State v. Cromey, 348 N.W.2d 759, 760 (Minn. 1984) (holding that defendant waived right to challenge admission of pathologist's testimony by failing to object at trial). We have reviewed the additional arguments Mwanza makes in his pro se brief, and we find them to be without merit.

We affirm Mwanza's conviction of fourth-degree assault, reverse his conviction of second-degree assault, and remand to the district court for resentencing.

  Affirmed in part, reversed in part, and remanded.

[ ]1 The baluster was approximately 30 inches long, and one inch square at the larger end, tapering to one-half inch square at the other end.